WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 31Citation - Scopus: 65The Performance of the Cms Muon Detector in Proton-Proton Collisions at Root S=7 Tev at the Lhc(IOP Publishing Ltd., 2013) Karapınar, GülerThe performance of all subsystems of the CMS muon detector has been studied by using a sample of proton-proton collision data at root s = 7TeV collected at the LHC in 2010 that corresponds to an integrated luminosity of approximately 40 pb(-1). The measured distributions of the major operational parameters of the drift tube (DT), cathode strip chamber (CSC), and resistive plate chamber (RPC) systems met the design specifications. The spatial resolution per chamber was 80-120 mu m in the DTs, 40-150 mu m in the CSCs, and 0.8-1.2 cm in the RPCs. The time resolution achievable was 3 ns or better per chamber for all 3 systems. The efficiency for reconstructing hits and track segments originating from muons traversing the muon chambers was in the range 95-98%. The CSC and DT systems provided muon track segments for the CMS trigger with over 96% efficiency, and identified the correct triggering bunch crossing in over 99.5% of such events. The measured performance is well reproduced by Monte Carlo simulation of the muon system down to the level of individual channel response. The results confirm the high efficiency of the muon system, the robustness of the design against hardware failures, and its effectiveness in the discrimination of backgrounds.Article Citation - WoS: 31Citation - Scopus: 32Alignment of the Cms Tracker With Lhc and Cosmic Ray Data(IOP Publishing Ltd., 2014) Karapınar, Güler; Demir, Durmuş AliThe central component of the CMS detector is the largest silicon tracker ever built. The precise alignment of this complex device is a formidable challenge, and only achievable with a significant extension of the technologies routinely used for tracking detectors in the past. This article describes the full-scale alignment procedure as it is used during LHC operations. Among the specific features of the method are the simultaneous determination of up to 200 000 alignment parameters with tracks, the measurement of individual sensor curvature parameters, the control of systematic misalignment effects, and the implementation of the whole procedure in a multiprocessor environment for high execution speed. Overall, the achieved statistical accuracy on the module alignment is found to be significantly better than 10 mu m.Article Citation - WoS: 458Citation - Scopus: 409Performance of Electron Reconstruction and Selection With the Cms Detector in Proton-Proton Collisions at Root S=8 Tev(IOP Publishing Ltd., 2015) Karapınar, GülerThe performance and strategies used in electron reconstruction and selection at CMS are presented based on data corresponding to an integrated luminosity of 19.7 fb(-1), collected in proton-proton collisions at root s = 8TeV at the CERN LHC. The paper focuses on prompt isolated electrons with transverse momenta ranging from about 5 to a few 100 GeV. A detailed description is given of the algorithms used to cluster energy in the electromagnetic calorimeter and to reconstruct electron trajectories in the tracker. The electron momentum is estimated by combining the energy measurement in the calorimeter with the momentum measurement in the tracker. Benchmark selection criteria are presented, and their performances assessed using Z, SIC, and J/psi decays into e(+)+e(-) pairs. The spectra of the observables relevant to electron reconstruction and selection as well as their global efficiencies are well reproduced by Monte Carlo simulations. The momentum scale is calibrated with an uncertainty smaller than 0.3%. The momentum resolution for electrons produced in Z boson decays ranges from 1.7 to 4.5%, depending on electron pseudorapidity and energy loss through bremsstrahlung in the detector material.Article Citation - WoS: 16Citation - Scopus: 24Reconstruction of Signal Amplitudes in the Cms Electromagnetic Calorimeter in the Presence of Overlapping Proton-Proton Interactions(IOP Publishing Ltd., 2020) Karapınar, Güler; CMS CollaborationA template fitting technique for reconstructing the amplitude of signals produced by the lead tungstate crystals of the CMS electromagnetic calorimeter is described. This novel approach is designed to suppress the contribution to the signal of the increased number of out-of-time interactions per beam crossing following the reduction of the accelerator bunch spacing from 50 to 25 ns at the start of Run 2 of the LHC. Execution of the algorithm is sufficiently fast for it to be employed in the CMS high-level trigger. It is also used in the offline event reconstruction. Results obtained from simulations and from Run 2 collision data (2015-2018) demonstrate a substantial improvement in the energy resolution of the calorimeter over a range of energies extending from a few GeV to several tens of GeV.Article Citation - WoS: 172Citation - Scopus: 509Jet Energy Scale and Resolution in the Cms Experiment in Pp Collisions at 8 Tev(IOP Publishing Ltd., 2017) Karapınar, GülerImproved jet energy scale corrections, based on a data sample corresponding to an integrated luminosity of 19.7 fb(-1) collected by the CMS experiment in proton-proton collisions at a center-of-mass energy of 8 TeV, are presented. The corrections as a function of pseudorapidity eta and transverse momentum (pT) are extracted from data and simulated events combining several channels and methods. They account successively for the effects of pileup, uniformity of the detector response, and residual data-simulation jet energy scale differences. Further corrections, depending on the jet flavor and distance parameter (jet size) R, are also presented. The jet energy resolution is measured in data and simulated events and is studied as a function of pileup, jet size, and jet flavor. Typical jet energy resolutions at the central rapidities are 15-20% at 30 GeV, about 10% at 100 GeV, and 5% at 1 TeV. The studies exploit events with dijet topology, as well as photon+jet, Z+jet and multijet events. Several new techniques are used to account for the various sources of jet energy scale corrections, and a full set of uncertainties, and their correlations, are provided. The final uncertainties on the jet energy scale are below 3% across the phase space considered by most analyses (p(T) > 30 GeV and vertical bar eta vertical bar < 5.0). In the barrel region (vertical bar eta vertical bar < 1.3) an uncertainty below 1% for p(T) > 30 GeV is reached, when excluding the jet flavor uncertainties, which are provided separately for different jet flavors. A new benchmark for jet energy scale determination at hadron colliders is achieved with 0.32% uncertainty for jets with p(T) of the order of 165-330 GeV, and vertical bar eta vertical bar < 0.8.Article Citation - WoS: 181Citation - Scopus: 382Performance of the Cms Muon Detector and Muon Reconstruction With Proton-Proton Collisions at Root S=13 Tev(IOP Publishing Ltd., 2018) Karapınar, Güler; CMS CollaborationThe CMS muon detector system, muon reconstruction software, and high-level trigger underwent significant changes in 2013-2014 in preparation for running at higher LHC collision energy and instantaneous luminosity. The performance of the modified system is studied using proton-proton collision data at center-of-mass energy root s = 13 TeV, collected at the LHC in 2015 and 2016. The measured performance parameters, including spatial resolution, efficiency, and timing, are found to meet all design specifications and are well reproduced by simulation. Despite the more challenging running conditions, the modified muon system is found to perform as well as, and in many aspects better than, previously. We dedicate this paper to the memory of Prof. Alberto Benvenuti, whose work was fundamental for the CMS muon detector.Article Citation - WoS: 10Citation - Scopus: 15An Embedding Technique To Determine Tau Tau Backgrounds in Proton-Proton Collision Data(IOP Publishing Ltd., 2019) Karapınar, Güler; CMS CollaborationAn embedding technique is presented to estimate standard model tau tau backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed mu mu events and replaced with simulated tau leptons with the same kinematic properties. In this way, a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS. Its validation and the inherent uncertainties are also discussed. The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at root s = 13 TeV corresponding to an integrated luminosity of 41.5 fb(-1).Article Citation - WoS: 9Citation - Scopus: 78Reconstruction and Identification of ? Lepton Decays To Hadrons and ?? at Cms(IOP Publishing Ltd., 2016) CMS Collaboration; Karapınar, GülerThis paper describes the algorithms used by the CMS experiment to reconstruct and identify τ → hadrons + νtau; decays during Run 1 of the LHC. The performance of the algorithms is studied in proton-proton collisions recorded at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb-1. The algorithms achieve an identification efficiency of 50-60%, with misidentification rates for quark and gluon jets, electrons, and muons between per mille and per cent levels.Article Citation - WoS: 208Citation - Scopus: 186Performance of Photon Reconstruction and Identification With the Cms Detector in Proton-Proton Collisions at ?s = 8 Tev(IOP Publishing Ltd., 2015) CMS Collaboration; Karapınar, GülerA description is provided of the performance of the CMS detector for photon reconstruction and identification in proton-proton collisions at a centre-of-mass energy of 8 TeV at the CERN LHC. Details are given on the reconstruction of photons from energy deposits in the electromagnetic calorimeter (ECAL) and the extraction of photon energy estimates. The reconstruction of electron tracks from photons that convert to electrons in the CMS tracker is also described, as is the optimization of the photon energy reconstruction and its accurate modelling in simulation, in the analysis of the Higgs boson decay into two photons. In the barrel section of the ECAL, an energy resolution of about 1% is achieved for unconverted or late-converting photons from Hγγ decays. Different photon identification methods are discussed and their corresponding selection efficiencies in data are compared with those found in simulated events. © CERN 2015 for the benefit of the CMS collaboration.Article Citation - WoS: 453Citation - Scopus: 360Identification of B-Quark Jets With the Cms Experiment(IOP Publishing Ltd., 2013) CMS Collaboration; Karapınar, GülerAt the Large Hadron Collider, the identification of jets originating from b quarks is important for searches for new physics and for measurements of standard model processes. A variety of algorithms has been developed by CMS to select b-quark jets based on variables such as the impact parameters of charged-particle tracks, the properties of reconstructed decay vertices, and the presence or absence of a lepton, or combinations thereof. The performance of these algorithms has been measured using data from proton-proton collisions at the LHC and compared with expectations based on simulation. The data used in this study were recorded in 2011 at s = 7 TeV for a total integrated luminosity of 5.0 fb-1. The efficiency for tagging b-quark jets has been measured in events from multijet and t-quark pair production. CMS has achieved a b-jet tagging efficiency of 85% for a light-parton misidentification probability of 10% in multijet events. For analyses requiring higher purity, a misidentification probability of only 1.5% has been achieved, for a 70% b-jet tagging efficiency. © 2013 IOP Publishing Ltd and Sissa Medialab srl.